Fungal diseases are common problems in crop agriculture. Many strides have been made against plant diseases as exemplified by the use of hybrid plants, pesticides and unproved agricultural practices. However, as any grower or home gardener can attest, the problems of fungal plant disease continue to cause difficulties in plant cultivation. Thus, there is a continuing need for new methods and materials for solving the problems caused by fungal diseases of plants. These problems can be met through a variety of approaches. For example, the infectious organisms can be controlled through the use of agents that are selectively biocidal for the pathogens. Another method is interference with the mechanism by which the pathogen invades the host crop plant. Yet another method, in the case of pathogens that cause crop losses, is interference with the mechanism by which the pathogen causes injury to the host crop plant. Still another method, in the case of pathogens that produce toxins that are undesirable to mammals or other animals that feed on the crop plants, is interference with toxin production, storage, or activity.
Within the Fusarium sp. are several important pathogens of corn and other cereals in various countries. In corn, Fusarium is known to cause root, stem and ear rot that results in severe crop reduction. The etiology of Fusarium ear mold is poorly understood, although physical damage to the ear and certain environmental conditions can contribute to its occurrence (Nelson, P. E., 1992, "Taxonomy and Biology of Fusarium moniliforme." Mycopathologia 117: 29-36). Fusarium may be isolated from most field grown maize, when no visible mold is present The relationship between seedling infection and the stalk and ear diseases caused by Fusarium is not clear. Genetic resistance to visible kernel mold has been identified (Gendloff E., Rossman E., Casale W., Isleib T., Hart P., 1986, "Components of resistance to Fusarium ear rot in field corn." Phytopathology 76: 684-688; Holley R. N., Hamilton P. B., Goodman M. M., 1989, "Evaluation of tropical maize germplasm for resistance to kernel colonization by Fusarium moniliforme." Plant Dis 73: 578-580). The mycotoxins produced by the Fusarium species that infect plants may accumulate in infected plants or in stored grains, presenting serious health consequences for livestock, humans and other consumers of meat or other food products of such livestock. Fusarium infection has been associated with chronic or acute mycotoxicoses in both farm animals and man (Botallico, et al.). An important mycotoxin that has been found to be produced by certain Fusarium sp. and has been identified in Fusarium-infected crops is moniliformin.
Moniliformin is a water-soluble toxin produced by Fusarium species such as Fusarium moniliforme and F. moniliforme var. subglutinans, as well as other species. These Fusarium species are found in virtually all food-grade corn worldwide, and moniliformin-producing isolates have been reported in Europe, South Africa, The United States, New Zealand, Taiwan and South America. It is likely that as more surveys are completed, moniliformin will be found at high levels in certain grain samples from a variety of areas. Moniliformin has been shown to have marked toxic effects toward animals and plants. It selectively inhibits mitochondrial pyruvate and alpha-ketoglutarate oxidations. Grain containing high levels of moniliformin may be restricted in its use or subject to important import/export regulations.
The discovery of bacteria that are able to metabolize moniliformin allows contaminated grain to be detoxified. This invention provides a bacterium that can grow on moniliformin as a sole or major carbon source. The degradation of moniliformin in the media may be assayed by a thin layer chromatography (TLC) assay. The present invention provides a method to reduce the amount of the mycotoxin in corn by incubation of infected corn with this bacterium or, alternatively, with the moniliformin-metabolization enzyme.
There is a need in the art for novel methods with which moniliformin may be eliminated from a plant or harvested grain. It is considered important by those skilled in the art to continue to develop inventions in order to protect the final consumer of a plant or harvested grain. The present invention provides the reagents and methodologies necessary to ameliorate plants and harvested grains from moniliformin.